Electrocatalysis rates, reason

In all experimental situations, some judgment must be made concerning the quality of the results.10 In this, it is important to understand the validity of the measurements, and the limits of error in the analytical determinations. In the case of electrocatalysis, the reaction rate on a catalyst surface is the most significant factor. Measurements of the reaction rate can easily be lower than the true reaction rate value but never higher. For this reason, the highest values must be given greater consideration than the lowest values. 

Changes of A from one metal to another, for a given process (e.g. the HER), provide the principal basis for dependence of the kinetics of the electrode process on the metal and are recognized as the origin of electrocatalysis associated with a reaction in which the first step is electron transfer, with formation of an adsorbed intermediate. In the case of the HER, this effect is manifested in a dependence of the logarithm of the exchange current density, I o (i.e., the reversible rate of the process, expressed as A cm , at the thermodynamic reversible potential of the reaction) on metal properties such as 0 (Fig. 2) (14-16, 20). However, as was noted earlier, for reasons peculiar to electrochemistry, reaction rate constants cannot depend on under the necessary condition that currents must be experimentally measured at controlled potentials (referred to the potential of some reference... 

It is remarkable that the erudite Rideal (a specialist in catalysis) did not introduce the term electrocatalysis in 1928. The reason, I think, was that electrochemistry in 1928 was generally focused on the electrode potential at a constant current and not the current (= rate) at a constant... 

Apart from the reaction steps involved in electrochemical and catalytic processes, there are other similarities. As we shall see in Chapter 3, electrochemical reaction rates can be increased by applying an electrical potential to the reacting surface. Indeed, a relatively modest electrode potential will be equivalent to raising the reaction temperature by several hundred degrees Celsius. The reason is that the applied potential reduces the height of the potential energy barrier that has to be overcome to make the reaction proceed. The analogous phenomenon in catalysis is the formulation of the catalyst to achieve the same objective. Further study of electrode processes indicates that intermediates adsorbed on an electrode surface will be able to modify a particular reaction route. We shall return to this phenomenon, called electrocatalysis, in Chapter 3. 

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